Brake



" are normally balanced.

atented Mar.. 15, 1938 UNlTeo STATES PATENT amati oFFlcE BR l Robert charles Louis rime got', Paris, France, assigner' to Bendix Brake Company, South Bend, d., a corporation oi' oisl Application .le 23, 193i, Serial. No. 546,342

, In ce l,lune 2t, i930 il@ Ulaims.

This invention relates to brakes and more particularly to brake operating devices and adjusting means therefor.

All hydraulic systems in which the desired operation is eiiected by the -increase in the pressure of a fluid are subjectv to a serious weakness, namely, that the system is incapacitated-.by the occurrence of a leak -in any part of the system, whereby the transmitting iluid may be lost and its pressure dissipated. In hydraulic brake systems this weakness is doubly important due to the great danger under which the failure of a braking system places the occupants of a ve hicle. This has been recognized in railway braking, resultingin the standard and required equipment of trains with reduction-pressure braking systems, but heretofore no method has been successfully and practically worked out for utilizing this reduction-pressure method for braking automotive vehicles.

It is, therefore, an object of the present invention to provide novel andl improved hydraulic braking means which operate to effect brake application on a reduction in the pressure of the ,uid in the system.

It isanother objectief thewinvention to provide a reduction pressure braking system utilizing -ture illustrating a control transmitting device constructed according to the invention. 4

Fig.A 3 is a view in elevation showing an application ofthe device to an automobile brake;

Y Fig. 4 is a view in elevation showlngan application of the device toA another automobile brake. f

Fig. 5- is a'longltudihal section showing the (adaptation of a similar controli device to the spring means both for brake application 'and brake release. J

Another object of the invention is to provide a braking system wherein the uid is usedto transmit pressures between two springs which Another object ofthe invention is to provide a braking system in which manual operation to initiate braking causes` expansionof the uid in the system, thereby releasing the operating spring.

Another object of lthe invention is to provide novel and improved automatically-operable means for effecting adjustment of the brake shoes lwith respect to the drum.

Another object of the invention is to provide automatic adjusting means for thLe brake shoes in which the movement of the adjusting means is always proportional to the movement of the brake shoes both in longitudinal and rotational movement of the adjusting means.-

A still further object of the invention isto provide 'novel and improved manually-operable means under control of the brake shoes withl respect to the drum, such adjusting means acting through the entire braking system to simultaneously adjust all the parts thereof.

Other objects 'and-features of novelty will be apparent from the following detailed description` when taken in connection with the accompanying drawings. It is to' be expressly understood however, that the drawings are for purposes of illustration only and are not .designed as a derlfront wheel of an automobile;

Fig. 6 is an elevation of an adjusting device for the control device; 'L y Fig. 7 is a side view of this samearrangement the same being partly in section;

Figs. 8 and 9 are views, similar to Figs. 6 and '1, of a modication of the adjusting device; and

Fig. 10 is a section taken on the line Ill-I0 of Fig. l to show the two rods 38. Y

According' to the form of construction shown in Fig. l, the control device is composed of two groups of elements, one, A, which is the trans-- mitter. is situated preferably at the actual controlling spot and directly connected with the operating mechanism, either lever or pedal. The other, B. which is the receiverpis situatedat any convenient distance from the former and directly coupled, to the controlled mechanism, brake jaws or any other. These two groups of 'elements, A fand B, are connected by a piping C containing the transmitting fluid. 1

In the transmitting group A, the pipe C. enters r, a cylinder I formed integrally with a'. housing 2 acting, preferably, as a tank for the liquid and also providingv trunnions for pivotally mounting thepedal, the lever or any other control element 3. A piston 4 slides in the cylinder rod Il.

at one end on lever 8 and at the other end on` the housing 2 and urges piston 4 in the direcl I. The cylinder I communicates with the tank 2 through a hole 5 inthe pwall of the said cylinder when this port is uncovered by the piston 4. A small cup 6 is pressed against the face of the piston on the same side as piping C by a weak spring 1 land insures' that there shall be no leakage in chamber 8.' A lever 9, 'fixed toJ a cross shaft I0 controls piston 4 through a A strong compression spring I2 bears tion of the arrow f1. The shaft I0 protrudes lI5 is slidably mounted in cylinder I5.

` A socket I9, perforated with holes 2D, is placed against the small cup I1 and retained by a spring 2l which rests'on the cover of the cylinder I5. This socket limits -the travel of piston I6 in the direction of the arrow f.

Piston I9 is connected to a rod 22 by /means' of a ball joint 23 which is integral with this rod. The joint 23 is loosely enclosed in piston Isso that it may be free to oscillate. A plug 24 is set,

, iorinstance, on piston I6`in order to prevent the ball joint y23 from leaving its recess. At the other end of rod 22 a yoke 25 is secured and connected with the elements to be controlled (this yoke 251s screwed on to the left in the example represented in Fig. 1).

'I'his yoke is connected to the element or elements to be controlled. For instance in the case of vehicle brakes shown in Figs. 3 and 4 two rods 25 and 21 are articulated both at one end in yoke 25 and on the other hand on the brake jaws 23-and 29. As shown the brake Jaws or shoes 25 and 29 (Figures 4 and 5) are arranged to be moved into contact with a rotatable brake drum 95.

Rod 22 can slide (Fig. 1) in a plug 30 closing the end of cylinder I5. This plug is screwed onto the cylinder for instance and locked by means of a locking piece 3l. A powerful spring 32 bears at one cnd on piston I5 and at the other end on a washer 33 which bears against the plug 33. This control gear is, preferably, fitted with an automatic adjusting. device. in the event of there being any wear of the element `controlled, which is particularly the case in the case of a brake control.

In the example represented in Fig. 1, a ring 34, provided with teeth 35, is fixed on rod 22 byv means such as'a cotter pin 35., This ring 34 engages with another ring 31 free to turn and' slide on rod 22. The teeth on these two rings only in one direction. Ring 31 is connected to the plug through rods 33 articulated by pins 33 and 40 von the said ring 31 and on plug 30. In this way when ring 31 Ymoves longitudinally in the direction of arrow P, rods 33 cornpel it to turn about rod 22 in the direction of arrow f4. A spring 4I which bears on the one hand on yoke 25 and on the other on ring 31keeps the latter in contact with ring 34.

Leather or rubber bellows 42 are attached at one end to cylinder I5 and at the other end to -plug 30 to protect the assembly from dust and water. This device includes, in addition.' at the upper end of the cylinder I5, a port 43 closed by a screw-plug 44 permitting the evacuation of the air or gases contained in cylinders I5 and I and the pipe line C when filling.v l

Operation is as follows: Tank 2, cylinders I and I5 and pipe line C being full of liquid, occupy positionsv indicated for each of them in Fig. 1 when at rest. In this position the power exerted by spring I2 on piston 41s balanced by ,the power exerted by spring 32 on piston I6.

This is easily realized by giving suitable values to the surfaces of pistons 4 and I6 and springs I2 and 32 (owing to .their weakness the action of springs 1, 2| and 4I need not be taken into account).

When pedal 3 is depressed, cross shaft `Ill is rotated in the direction of arrow f4. Lever 9 compresses spring I2 which reduces the pressure of the liquid in proportion 'withlthe travel of the pedal. The equilibrium of pressure in cylinder I5 is destroyed and piston I 6 moves forward in the direction oi arrow I under the action of. a force equal to the pressure of spring 32 less the force of the pressure of the liquid.

If the travel of the pedal is such that the small cup 6 uncovers port 5, and inasmuch as the upper part of the reservoir 2 is vented as at 2a to the atmosphere the liquid contained in the pipe line C and in cylinders I and I5 is under atmospheric pressure. The result is that the eiiort applied on piston I6 and on rod 22 in the direction of arrow f2 4is equal to the pressure of spring 32. l

Therefore, on pedal 3 being depressed, as the pressure of the liquid diminishes, pistonv I6 and rod 22 move in the direction of arrow f2, owing to the action of spring 32. The elements connected with yoke 25 follow this movement.

For instance (Figs. 3 and 4) if the yoke 25 moves upward the brake shoes 28 and 29 are pushed apart and applied against the drum while ensuring an equal distribution of the effort on each jaw. Moreover in cases Where the device is applied to brakes acting on the full iioating system (Fig. 4) the drive of one of the shoes, (shoe 28 for instance if the drum is revolving ir. the direction of arrow f5) causes the brake applying eilect of yoke 25 which'isr already being driven upward by spring 32 to be augmented by the servo bralnng effect applied to shoes 23 and 29. 'Ihis servo-braking effect reduces the eilort to be applied to the pedal `by the driver to lan equal extent.

It should be noted that if a leak occurs in the pipe line C or in cylinders I and I5, the pressure of the liquid drops as is the 'case if one presses pedal 3 to the end of its travel so that, for instance, in the adaptation of-this device to the brakes of a vehicle a leak would cause immediate braking. f

When pedal 3 is released, whether port 5 has been openedA or not by cup 6, spring I2 compresses the liquid and piston 4 is driven in the direction of arrow f1 until it reaches the position of equilibrium it occupied originally, this position depending on the position of the piston 4 as determined by the screw I3 and upon the amount of liquid trapped`between the pistons' 4 and I5. Piston I6 'and yoke 25 also return to their rest position releasing shoes 28 and 29 and the other organs they control. It will be seen -that the shoes are always operated in either direction strictly in accordance with the wish of the operator. It is not necessary that hole 5 should be opened every time the pedal is actuated (this is only necessary when iilling). In order to apply the brakes, it is necessary to compress the spring I2. Acting toward the compression of the spring I2, there may be two -forces-flrstof the spring 32 acting through the fluid link and second the force exerted physically on the pedal 3. Thus although the spring 32 actually moves the rod 22`to apply the brakes, the fOrce it exerts towards applying said brakes dil is governed by the amount of force exerted on the pedal 3 to aid in compressing or wholly compressing the spring i t.

'The shoes 2d and'd of Figure 4 are joined to each other at the lower ends by a `shoe link pin di so that they move together. When the brake is applied initially by the actionofjthe toggle ttld-3l, the upper ends of the shoes are spread apart in to drum contact. Thereupon the rotating drum moves the shoes to anchor (de-4 pending upon the direction` of drum rotation) vupon the anchor pin dt orthe anchor pin dt. IrlFhis'movernent of the two shoes is thus accomv tween shoes lt and td andthe brake drum in the case of a brake, it will be necessary to reduce length Xi! of rod tt by an amount in proportion to that wear. l lt is for that reason and to heep thetravel oi the pedal t constant that the )automatic adjustment described above has been the direction of arrow i3 owing'to the fact that it,

is connected with plug it by rods td. When the `travel of ring ld reaches'a certain value, determined in advance, ring 'tl turns, in relation to ring til, by the value of one tooth. When ring dit returns to its initial position Vit presses hard on ring dl which, when it approaches plug til, is compelled to rotate in a direction opposite to that of arrow f3 drawing along, in its rotating motion, ring di and rod tt. Rod tt therefore screws into yoke 25 and thus reduces the distance Xl? between the yoke and ball joint t3 by the required amount. Itis necessary to calculate properly the pitch of teeth Sit, the length and the displacement of rods t8 and the thread of rod tt.-

F'lgure 2 represents another method of realizationl of transmitting group A. ln the example set\ forth cylinder i communicates with a separate tank 46 through piping 4l and a side port it which can be opened and shut by piston t.

Cylinder Il is closed at one end by plug it preferably screwed into it, a cup td between the cylinder and the plug resting on a. shoulder insaid cylinder i -The cup 49 is held against the plug 4B by a spring 5l resting on the one hand on this socket 50 and on the other hand on the.

and prevents any loss of the liquid contained in the annular space. 53.

The cup 49 is preferably of rubber or`other similar resilient lsealing material. A portl 54 in ,fthe side wall of cylinder i ,places space 53 incommunication with tank 46, thus permitting the return of` the liquid into this tank when piston 4 moves in a direction opposite aliased the direction or arrows f5 and f".

spring urging piston t in the direction ot arrow f1.

The operation of this system is the same as in the case of the arrangement described previously,lthe pressure of the liquid being reduced when one depresses the pedal t against spring it in a reverse direction to arrow f1.

The control system represented in Figure 5 ls applied to the iront wheel oi an automobile. In this example of application, cylinder it is vfixed to the swivelling spindle tt or the wheel,

the axle of which is shown at tl and one of the stub axles at tt. Piston it is cambered and cup il made tight in such a way that it cannot slide. Operation is the same asin the example shown in Figure 1, except that cup il having its outer edges `secured to the cylinder and-being formed of elastic deformable material, does not slide within the cylinder but transmitsmotion to the piston by reason of the deformation of the center of the cup. A

For preterence the control system comprises an adjusting device which permits of modifying rapidly and at will, in either direction, the rest position of the moving components of the control system, while the operating pedal retains an invariable rest position. In the examples shown in Figures 6 to i), pedal d is tted loose on shaft it and bears, by means of a cam' tt which canbe made fast in any desired position, on a lever td which is'rigid with shalt ill.

Pedal t (lodigures 6 and 7) comprises a yolre ti in which a shaft tt is free to oscillate. 0n this shaft two toothed wheelsttl and dit, are hired and, preferably between these two wheels is provided a cam iid. Wheel tt which is not shown on Figure 6 bears teeth placed in an inverse position to those on wheel tt. A push rod th placed to act edecti'vely above ,(as shwn in Figure 6) can control wheel til and another rod tt placed to act eectivelyy below (as shown in Figure t) the axis tt of the wheel tt can control wheel dt. These two rods are articulated to an edualizing lever tl comprising two placesV tt and td and itself articulated at ltzso that it can osoillate in Two springs 'lll guided by rods th and tt, rest at one end on a door or base 'it and at the other end on the ends of equalizing lever tl, urging the latter to its rest position. l hxed check ld permanently determines the rest position of pedal t. lltls toV be understood that the openings through the loorboard llt are suiciently large to permit )the operation of the rods t5 and tt without jamming.

The adjustment of the control element is edectedl as follows: Depression of end 69 of the equalizing lever 6l pushes rod 65 thereby causing wheel 64 to rotate and consequently cam 59 inthe direction of' arrow f. Owing to the shape of the cam, lever 6U comes nearer pedal 3 and -drives shaft i0 in `a direction reverse to arrow f4. This causes a displacementof piston 4 in the direction of arrow f1; an increase in the pressure of the transmitting liquid, ,and a displacement ofvpiston i6, rod 22 and yoke 25 in a dlrectioncontllary 'to that of arrow f2. The effect of this displacement is to bring kjaws 28 and 29 (Figures 3 and 4) v nearer one another, thus reducing the play between .the said jaws and the brake drum. It is thus possible, from the' drivers seat and even while the car is moving, to loosen the brakes should they remain. on.

jaws 28 and 29 and lthe brake, in/the/conty case. All one has to do/is/topress on the end Zilli` Itis also possible to reduce the play between/ 66 of equalizing lever 61. Rod 66 acts on ther toothed wheel -63 and causes it to rotate, as well as cam 59, in a directionco'ntrary'to that'of arrow f". Lever 60 moves away from pedal 3 and makes shaft l rotate and this causes a reduction of pressure in the transmitting liquid and the displacement of the yoke in the direction of arrow P. i 4 f Figures 8 and 9 represent a similar arrangement in which the control of cam 59 is effected Aby chains or ycables and by hand. In this arrangement -a plate 14 is rigid with a shaft 62 solid with cam 59. 0n this plate, on either side of fshaft 62, the ends of two cables 15 and 16 are attached and their other ends are attached to the ends of a chain 11 which passes over a toothed wheel 18. A handle 19 is s olid with wheel 18. Handle 19, wheel 18 and chain 11 may be placed, for instance, on the dash of the car. The cables 16, and 16 are carried on one or more idler pulleys III. 'I'hey valso pass through the grooves 8i and 62 of pedal 3 so that in its rotation this pedal may not "influence the length of the cables and consequently the adiustment. It is to be understood that-in the arrangements shown in Figures v 7 to 10 inclusive, the pedal 3 is loose on the shaft I6 and the lever 60 is fixed on the shaft I0.

Operation is the same asin the preceding'case. It is sufficient to turn handle l19 one way or the other.

While there has been shown and described one embodiment of the invention, it is to be understood thatl the invention is not limited thereto. Various chan es lin the shapes, sizes and .manner of assem ling the various component parts may be resorted to without departing from the scope of the invention, as will occur to those skilled in the art. Reference will therefore be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

l. In a Kbraking device comprising brake applying and releasing means, hydraulic means associated with both said means, manual means for controlling the action of said hydraulic means, a lever operable to vary the effect of said manual means, and means for operating said lever.

2. A braking system comprising a rotatable friction element, an anchored friction` element. `means for urging said anchored friction element into contact with said rotatable friction element, hydraulic means for making said urging means ineffective, a slack take-up device associated with said anchored friction element, said device including means operated bythe increase of clearance between the anchored friction element and the rotatable friction element to a certain predetermined distance for operating said slack take-up vdevicef 3. A braking system comprising a rotatable friction element; an anchored friction element; means for urging said anchored `friction element into contact with said rotatable friction element; hydraulic means for making said urging means ineffective Yand a slack take-up device associated with said anchored friction element, said slack take-up device comprising a member, a screw threaded in said member, a .stationary element through which said screw is adapted to slide, a collar loosely mounted upon said screw and formed with teeth, an applying link secured to said stationary element and to said collar, and

a collar secured to said screw and having teeth cooperating with the teeth of said iloating collar.

4. In a hydraulic braking apparatusg a pedal arm, aA shaft upon which said pedal arm is mounted, a second arm secured to said shaft, a cam interposed between said arms, a master cylinder having a piston movable therein, means operatively connecting said shaft to said piston. and means convenient to the operator of said vehicle for rotating said cam.

5. In a hydraulic braking apparatus, a pedal arm; a shaft upon which said pedal arm is mounted; a second arm secured to said shaft; a cam interposed between said arms; a master cylinder having a piston movable therein; means operatively connecting said shaft to said piston; and means convenient to the operator `of said vehicle for rotating said cam, said rotating means comprising a pair of ratchet wheels connected to said cam, a pair of rods associated respectively with said ratchet wheels, and a pedal connected to said arms.

6. In ahydraulic braking apparatus; a pedal arm; a shaft upon which said pedal arm is mounted; a second arm secured to said shaft; a cam interposed between said arms; a master cylinder having a piston movable therein; means operatively connecting said shaft to said piston;

.and means convenient to the operator of said vehicle for rotating said cam, said rotating means comprising a tension element connected to said cam, and a handle operatively connected to said tension elements '1. A brake system comprising a drum, an anchored friction element positioned in said drum, means for urging said anchored friction element intocontact with said drum, hydraulic means for making said urging means ineffective, and a slack take-up device positioned in said drum, said device including means operated by the increase of clearance between the drum and the friction element to a certain predetermined distance for operating said slack take-up device.

8. A braking device comprising brake applying and releasing means, hydraulic means associated with both said means, manual means for controlling the action of said hydraulic means, a lever .operable to vary the eiIect of said manual means, means' for operating said lever, a pivot for said lever also carrying said manual means, a cam carried by said manual means and cooperating with said operating means lfor said lever, and means for operating said cam.

9. In a braking device comprising brake applying and releasing means, hydraulic means associated with both of saidmeans, manual means for controlling the action of said hydraulic means, a lever operable to vary the effect of said manual means, means for operating said lever, a rotatable shaft carried by said manual means, a cam on said shaft, a gear wheel car- `ried by said shaft, and means to rotate said gear wheel.

l0. In a braking device comprising brake applying and releasing means, hydraulic means associated with both said means, manual means for controlling the action of said hydraulic means, a lever operable to vary the eect of said Y manual means, means( for operating said lever, a rotatable shaft carried by said manual means, a cam carried by said shaft, a plurality of toothed wheels carried by said shaft, and means to selectively rotate said toothed wheels to effect rotation of said cam to thereby vary the pressure of said hydraulic means.

ROBERT CHARLES LOUIS PIERRE TURGOT. 

